U.S. patent application number 10/439742 was filed with the patent office on 2003-11-20 for scanning microscope and beam deflection device.
This patent application is currently assigned to Leica Microsystems Heidelberg GmbH. Invention is credited to Engelhardt, Johann.
Application Number | 20030214707 10/439742 |
Document ID | / |
Family ID | 7971298 |
Filed Date | 2003-11-20 |
United States Patent
Application |
20030214707 |
Kind Code |
A1 |
Engelhardt, Johann |
November 20, 2003 |
Scanning microscope and beam deflection device
Abstract
A scanning microscope has a light source that generates a light
beam for illumination of a specimen, and has a beam deflection
device with which the light beam can be guided over the specimen.
The beam deflection device contains at least one rotatable unit
having at least one reflecting mirror. A compensation element that
executes a motion equal and opposite to that of the rotatable unit
is arranged in such a way that it at least partially compensates
for the moment of inertia of the rotatable unit.
Inventors: |
Engelhardt, Johann; (Bad
Schoenborn, DE) |
Correspondence
Address: |
DAVIDSON, DAVIDSON & KAPPEL, LLC
485 SEVENTH AVENUE, 14TH FLOOR
NEW YORK
NY
10018
US
|
Assignee: |
Leica Microsystems Heidelberg
GmbH
Mannheim
DE
|
Family ID: |
7971298 |
Appl. No.: |
10/439742 |
Filed: |
May 16, 2003 |
Current U.S.
Class: |
359/385 ;
359/368; 359/390 |
Current CPC
Class: |
G02B 21/002
20130101 |
Class at
Publication: |
359/385 ;
359/368; 359/390 |
International
Class: |
G02B 021/06 |
Foreign Application Data
Date |
Code |
Application Number |
May 18, 2002 |
DE |
DE 202 07 817.5 |
Claims
What is claimed is:
1. A scanning microscope comprising: a light source that generates
a light beam for illumination of a specimen; a beam deflection
device with which the light beam can be guided over the specimen,
the beam deflection device containing at least one rotatable unit
having at least one reflecting mirror; and a compensation element
that executes a motion equal and opposite to that of the rotatable
unit which is arranged in such a way that it at least partially
compensates for the moment of inertia of the rotatable unit.
2. The scanning microscope as defined in claim 1, wherein the
compensation element at least partially compensates for the moments
of inertia of further movable components.
3. The scanning microscope as defined in claim 1, wherein the
reflecting minor is tiltable and/or pivotable about a first
axis.
4. The scanning microscope as defined in claim 3, wherein the
compensation element is rotatable about a second axis that is
parallel to the first axis.
5. The scanning microscope as defined in claim 3, wherein the
compensation element is rotatable about a third axis that is
parallel to the first axis.
6. The scanning microscope as defined in claim 4, wherein the
compensation element and the rotatable unit are mechanically
coupled to one another with at least one belt that transfers drive
energy.
7. The scanning microscope as defined in claim 5, wherein the
compensation element and the rotatable unit are mechanically
coupled to one another with at least one belt that transfers drive
energy.
8. The scanning microscope as defined in claim 1, wherein a drive
drives the beam deflection device.
9. The scanning microscope as defined in claim 8, wherein the drive
also drives the compensation element.
10. The scanning microscope as defined in claim 8, wherein the
compensation element is a constituent of the drive.
11. The scanning microscope as defined in claim 8, wherein the
drive is a galvanometer.
12. The scanning microscope as defined in claim 8, wherein the
compensation element has a further drive that is synchronized with
the drive of the beam deflection device.
13. A confocal scanning microscope comprising: a light source that
generates a light beam for illumination of a specimen; a beam
deflection device with which the light beam can be guided over the
specimen, the beam deflection device containing at least one
rotatable unit having at least one reflecting mirror; and a
compensation element that executes a motion equal and opposite to
that of the rotatable unit which is arranged in such a way that it
at least partially compensates for the moment of inertia of the
rotatable unit.
14. The confocal scanning microscope as defined in claim 13,
wherein the compensation element at least partially compensates for
the moments of inertia of further movable components.
15. The confocal scanning microscope as defined in claim 13,
wherein the reflecting mirror is tiltable and/or pivotable about a
first axis.
16. The confocal scanning microscope as defined in claim 15,
wherein the compensation element is rotatable about a second axis
that is parallel to the first axis.
17. A beam deflection device for a scanning microscope with which a
light beam can be guided over a specimen, the beam deflection
device comprising: at least one rotatable unit having at least one
reflecting mirror, a compensation element that executes a motion
equal and opposite to that of the rotatable unit is arranged in
such a way that it at least partially compensates for the moment of
inertia of the rotatable unit.
18. The beam deflection device as defined in claim 17, wherein the
compensation element at least partially compensates for the moments
of inertia of further movable components.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Priority is claimed to German utility model application 202
07 817.5, which is hereby incorporated by reference herein.
FIELD OF THE INVENTION
[0002] The invention concerns a scanning microscope and a confocal
scanning microscope.
[0003] The invention further concerns a beam deflection device for
a scanning microscope.
BACKGROUND OF THE INVENTION
[0004] In scanning microscopy, a specimen is illuminated with a
light beam in order to observe the detected light emitted, as
reflected or fluorescent light, from the specimen. The focus of an
illuminating light beam is moved in a specimen plane by means of a
controllable beam deflection device, generally by tilting two
mirrors; the deflection axes are usually perpendicular to one
another, so that one mirror deflects in the X direction and the
other in the Y direction. Tilting of the mirrors is brought about,
for example, by means of galvanometer positioning elements. The
power level of the detected light coming from the specimen is
measured as a function of the position of the scanning beam. The
positioning elements are usually equipped with sensors to ascertain
the present mirror position.
[0005] In confocal scanning microscopy specifically, a specimen is
scanned in three dimensions with the focus of a light beam.
[0006] A confocal scanning microscope generally comprises a light
source, a focusing optical system with which the light of the
source is focused onto an aperture (called the "excitation
pinhole"), a beam splitter, a beam deflection device for beam
control, a microscope optical system, a detection pinhole, and the
detectors for detecting the detected or fluorescent light. The
illuminating light is coupled in via a beam splitter. The
fluorescent or reflected light coming from the specimen travels
back through the beam deflection device to the beam splitter,
passes through it, and is then focused onto the detection pinhole
behind which the detectors are located. Detected light that does
not derive directly from the focus region takes a different light
path and does not pass through the detection pinhole, so that a
point datum is obtained which results, by sequential scanning of
the specimen, in a three-dimensional image. A three-dimensional
image is usually achieved by acquiring image data in layers.
[0007] German Unexamined Application DE 43 22 694 A1 describes a
confocal microscope containing a scanner arrangement in which the
deflection arrangement along the X axis contains two resonance
scanners that oscillate about parallel axes at different
frequencies, one of which is a harmonic of the other. As a
consequence thereof, scanning along the X axis can be performed
almost linearly even though it occurs in conjunction with a
resonance, and advantages associated with the rapidity of resonance
systems can therefore be achieved. A galvanometer rotates the
housing of one of the resonance scanners about its axis in order to
achieve an X-axis pivoting function.
[0008] German Patent DE 196 54 210 C2 discloses an optical
arrangement for scanning a beam in two axes lying substantially
perpendicular to one another, in particular for use in confocal
laser scanning microscopes. In order to eliminate serious
aberrations, the optical arrangement, which has two mirrors
rotatable by means of respective drives about mutually
perpendicular axes (X axis and Y axis), is characterized in that
one of the two mirrors has a further mirror associated nonrotatably
with it in a predefined angular position, so that the mirrors
associated with one another (first and second mirrors) rotate
together about the Y axis and thereby rotate the beam about a
rotation point that lies on the rotation axis (X axis) of the third
mirror which rotates alone.
[0009] German Unexamined Application DE 42 05 725 A1 discloses a
galvanometer that encompasses a cylindrical magnetic rotor which is
polarized into two substantially semi-cylindrical poles on opposite
sides of its axis. A rotor is shown that comprises a thin-walled
torque-absorbing sleeve which surrounds at least a portion of the
magnet and is joined to the output shaft and to the magnet. An
attachment means anchors the coil body to the shell in order to
prevent relative rotation therebetween.
[0010] The known scanning microscopes have the disadvantage,
especially at high scanning rates, that because of the inertia of
the moving components of the beam deflection device, troublesome
vibrations and mechanical oscillations are transferred therefrom to
the scanning microscope and the specimen. This results not only in
degraded image acquisition but also in damage to the specimen when
micro-instruments protruding into the specimen--such as
micropipettes, microelectrodes, or patch clamps--are used.
[0011] Galvanometers, such as e.g. the galvanometer known from the
aforementioned DE 42 05 725 A1, have a sleeve (having the greatest
possible inertia) that is intended to absorb the torque generated
by the rotor. This is not sufficient, however, if further
protruding high-inertia elements are attached to the rotor.
Arrangements for beam deflection such as those known from German
Patent DE 196 54 210 C2 already cited are, in particular, unusable
at high line scanning rates because of the mirror carrier which
protrudes a great distance from the rotation axis.
SUMMARY OF THE INVENTION
[0012] It is therefore an object of the present invention to
describe a scanning microscope in which mechanical disturbances and
vibrations caused by the beam deflection device are eliminated or
at least reduced.
[0013] The present invention provides a scanning microscope
comprising:
[0014] a light source that generates a light beam for illumination
of a specimen
[0015] a beam deflection device with which the light beam can be
guided over the specimen, the beam deflection device containing at
least one rotatable unit having at least one reflecting mirror,
[0016] a compensation element that executes a motion equal and
opposite to that of the rotatable unit which is arranged in such a
way that it at least partially compensates for the moment of
inertia of the rotatable unit.
[0017] A further object of the invention is to describe a beam
deflection device for a scanning microscope that for the most part
transfers no troublesome mechanical excursions or vibrations to the
scanning microscope.
[0018] The present invention also provides a beam deflection device
with which a light beam can be guided over a specimen, the beam
deflection device comprising: at least one rotatable unit having at
least one reflecting mirror, a compensation element that executes a
motion equal and opposite to that of the rotatable unit is arranged
in such a way that it at least partially compensates for the moment
of inertia of the rotatable unit.
[0019] The invention has the advantage that the risk of damage to
the specimen is decreased, and that good image quality is
guaranteed even at high scanning rates.
[0020] In a preferred embodiment, the reflecting mirror is tiltable
or pivotable about a first axis. In another embodiment, a housing
within which the reflection mirror is positioned is mounted on the
rotation shaft of the drive. A pivot arm can also be provided. The
rotatable unit can contain, for example, a mirror substrate, or
also a more complex holder, carrier, or retaining arm.
[0021] In a preferred embodiment, the compensation element
compensates at least partially for the moment of inertia of further
movable components. The further movable components can include
drive elements of the scanning microscope or of the beam deflection
device, for example of a galvanometer or motor, or components for
energy transfer.
[0022] In a preferred embodiment, the drive pivots a first
reflecting mirror, arranged on a pivot arm, about a rotation axis.
A second reflecting mirror, which is equipped with a separate drive
and is pivotable about a further rotation axis perpendicular to the
rotation axis, serves, in the context of meander-shaped scanning of
the specimen, for scanning the scanning points within the lines (X
deflection), while the first reflecting mirror serves to scan the
lines (Y deflection). The rotation shaft of the drive is coupled
via a largely zero-backlash linkage to the compensation element,
which is embodied e.g. as a solid cylinder and has the same moment
of inertia as the first and the second reflection mirror together
with their mounts and pivot arms. Because of the coupling, the
compensation element rotates in equal and opposite fashion about a
second axis that is parallel to the first axis. The compensation
element can also be embodied as a pivot anchor that pivots about
the second axis.
[0023] In a preferred embodiment, the compensation element and the
rotatable unit are mechanically coupled to one another with belts
that transfer the drive energy. This embodiment is particularly
efficient because energy transfer is accomplished in largely
zero-backlash fashion, which is advantageous especially upon
reversal of the direction of motion. In this form, the drive also
drives the compensation element. It is also possible for the
rotatable unit and reflection mirror and the compensation element
to have different drives that are e.g. electronically synchronized
with one another.
[0024] In another variant embodiment, the compensation element is a
constituent of the drive.
[0025] Motors of any kind, for example electric motors or stepping
motors, and in particular galvanometer drives, are usable as the
drive.
[0026] In a preferred embodiment, the scanning microscope is a
confocal scanning microscope.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The subject matter of the invention is schematically
depicted in the drawings and will be described below with reference
to the Figures, identically functioning elements being labeled with
the same reference characters. In the drawings:
[0028] FIG. 1 shows a scanning microscope according to the present
invention;
[0029] FIG. 2 shows a beam deflection device for a scanning
microscope; and
[0030] FIG. 3 illustrates the mechanical coupling of the
compensation element within a beam deflection device.
DETAILED DESCRIPTION OF THE INVENTION
[0031] FIG. 1 shows a scanning microscope 1 according to the
present invention that is embodied as a confocal scanning
microscope, having a light source 3 that emits a light beam 5 for
illumination of a specimen 7. Light beam 5 is focused onto an
illumination pinhole 9 and is then reflected by a dichroic beam
splitter 11 and a downstream reflecting mirror 13 to beam
deflection device 15, which guides light beam 5 via scanning
optical system 17 and tube optical system 19, through microscope
optical system 21 and over or through specimen 7. Detected light
beam 23 proceeding from specimen 7 travels through microscope
optical system 21 and via tube optical system 19, scanning optical
system 17, and beam deflection device 15 to dichroic beam splitter
11, passes through the latter and detection pinhole 25 after it,
and lastly arrives at detector 53, which is embodied as a
photomultiplier. In detector 53, electrical detected signals
proportional to the power level of detected light beam 23
proceeding from the specimen are generated. The specimen is scanned
in layers so as to generate, from the detected signals, a
three-dimensional image of specimen 7.
[0032] Beam deflection device 15 contains a unit 29, rotatable
about a first axis 27, which contains two reflective surfaces 31,
33 stationary with respect to one another--i.e. a first reflective
surface 31 and a second reflective surface 33--and receives light
beam 5 and conveys it to a third reflective surface 35 that is
rotatable about a second axis 37 (perpendicular to the paper plane
in the Figure) that extends perpendicular to first axis 27. In the
region between reflecting mirror 13 and first reflective surface
31, light beam 5 extends along first axis 27. Rotatable unit 29 has
a further reflective surface 39, stationary with respect to first
reflective surface 31 and second reflective surface 33, that
receives the light beam from first reflective surface 31 and
reflects it to second reflective surface 33. Rotatable unit 29 is
driven by a galvanometer 41. Third reflective surface 35 is
deposited onto a third mirror substrate 43; the substrate is driven
by a galvanometer (not shown in the Figure). First reflective
surface 31 is deposited on a first mirror substrate 45, second
reflective surface 33 on a second mirror substrate 47, and further
reflective surface 39 on a further mirror substrate 49. Rotatable
unit 29 has a housing 51 that encloses the reflective surfaces and
protects them from contamination. Certain optical elements for
guiding and shaping the light beams are omitted from the Figure in
the interest of better clarity. These are sufficiently familiar to
the person skilled in this art.
[0033] Galvanometer 41 pivots rotatable unit 29 about first axis
27. Energy transfer is accomplished via a drive shaft 67. Mounted
on drive shaft 67 is an entrainment disk 55 that is coupled via a
flat flexible belt 57 to compensation element 59 in such a way that
the latter pivots about a third axis 61 in the opposite direction
from rotatable unit 29. Compensation element 59 is a cylinder that
has the same moment of inertia with respect to third axis 61 that
rotatable unit 29, including the other moving components, has with
respect to first axis 27. Galvanometer 41 could also be arranged so
that it primarily drives compensation element 59, and so that
rotatable unit 29 is driven via the entrainment disk.
[0034] FIG. 2 is a perspective view of a beam deflection device 15
for a scanning microscope. Beam deflection device 15 contains a
unit 29, rotatable about a first axis 27, which contains two
reflective surfaces 31, 33 stationary with respect to one
another--i.e. a first reflective surface 31 and a second reflective
surface 33 and receives light beam 5 and conveys it to a third
reflective surface 35 that is rotatable about a second axis 37 that
extends perpendicular to first axis 27. Rotatable unit 29 has a
further reflective surface 39, stationary with respect to first
reflective surface 31 and second reflective surface 33, that
receives the light beam from first reflective surface 31 and
reflects it to second reflective surface 33. Third reflective
surface 35 is deposited onto a third mirror substrate 43; the
substrate is driven by a resonant galvanometer 65 via a further
drive shaft 67. First reflective surface 31 is deposited on a first
mirror substrate 45, second reflective surface 33 on a second
mirror substrate 47, and further reflective surface 39 on a further
mirror substrate 49. Rotatable unit 29 has a housing 51 that
encloses the reflective surfaces and protects them from
contamination. A reflecting mirror 13 that reflects light beam 5
onto first rotation axis 27 is additionally provided.
[0035] Rotatable unit 29 is driven indirectly. A galvanometer 41
pivots a compensation element 59 that is mechanically coupled, via
a flat flexible belt (not shown in this Figure) and an entrainment
disk 55 and a drive shaft 67, to rotatable unit 29 in such a way
that the latter pivots in the opposite direction from compensation
element 59. The rotation pulses of the pivoting components are
thereby largely compensated for, so that almost no drive energy is
transferred to the surrounding scanning microscope.
[0036] FIG. 3 illustrates one possibility for mechanically coupling
compensation element 59 to rotatable unit 29 within a beam
deflection device 15 using a flat belt 57 that has at one end, in
the central region, a slit 69 through which the tapered other end
71 is guided. Belt 57 wraps around compensation element 59 and at
its ends is placed around rotatable unit 29 (or around an
entrainment disk coupled thereto) and attached to it. A
particularly low-backlash coupling is thereby obtained.
[0037] The invention has been described with reference to a
particular exemplary embodiment. It is self-evident, however, that
changes and modifications can be made without thereby leaving the
range of protection of the claims below.
* * * * *